Asymmetric reduction of ketones

Nakamura,.; Itoh,.(10) Hydrosilylation may be used to reduce ketones after silyl ether hydrolysis.Indeed, TONs well in excess of promo monalbumphoto 10,00020,000 have been reported for substrates of industrial relevance, and vtt en promo in several cases even higher TONs ( rab ne bana di jodi ringtone 100,000) have been reported.Li,.; Wu,.; Chen,.; Hancock,.; King,.; Xiao,.Good TONs (such as TON 5000) have been achieved in industrial processes ( 26 ).The technology for the catalytic asymmetric reduction of ketones now covers a large spectrum of substrates, including highly complex and functionalised molecules.The design of paracyclophane-based ligands has been extended to a new class of ligand: ParaPhos, 4, ( 11 ).Palladium-Catalysed Asymmetric Hydrogenation Zhou and co-workers from the Chinese Academy of Sciences (PRC) ( Org."Baker's yeast mediated transformations in organic chemistry".The catalyst ( R,R )- 11 showed less regioselectivity, and alcohol 8 (R nhco2Me) was isolated in only 7 yield.However, developments are still needed and new technology required to meet the challenges of processes, such as the hydrogenation of aliphatic ketones and reductive amination.In the mid 1990s, Noyori's group developed a second generation of catalysts.Biarylphosphines ligands, based on binap, 1, see, figure 2, proved to be highly successful in Noyori's second generation catalysts.They found that binap-ruthenium catalysts were useful for the hydrogenation of functionalised ketones (such as -ketoesters, -amino- ketones and -hydroxy- ketones ) that possessed secondary binding groups capable of coordinating the substrate to the reactive ruthenium metal centre in the form of 5- and 6-membered.The cost of the catalyst is offset by its high productivity unprecedented for many catalytic asymmetric reactions.